Dielectric materials used in the semiconductor industry have shifted from silicon oxide to porous low-k materials in an effort to reduce dielectric constant and increase performance of integrated circuits. Porous low-k materials with dielectric constants as low as two have been developed. However, porous low-k films are more susceptible to damage from diffusion or plasma processing damage. For example, the porosity may allow process gases or water to penetrate into the low-k dielectric material during some processing operations, such as etching, ashing or CMP. The resulting damage may undesirably increase the dielectric constant of low-k dielectric films. Incorporating a poresealing process may undo damage and also decrease the dielectric constant but may also keep undesirable chemicals from entering the low-k dielectric during subsequent processing. Poresealing processes are used to form a stable thin dielectric barrier spanning the pores. During the poresealing process, poreseal may also undesirably deposit on exposed metal surfaces of a patterned substrate. Poreseal interfaces at electrical connections may increase the resistance and sacrifice performance in a completed device.
Objects of the embodiments presented herein include preventing poreseal residue formation on exposed metal or facilitating removal of the poreseal undesirably formed on exposed metal surfaces.